Add input-switch

Moving common stuff for DDC/CI communicating programs to ddc-ci.c.

1 files changed, 246 insertions, 0 deletions

diff --git a/ddc-ci.c b/ddc-ci.c
new file mode 100644
index 0000000..0edce8a
--- /dev/null
+++ b/ddc-ci.c
@@ -0,0 +1,246 @@
+/*
+ * ddc-ci.c: DDC-CI utilities, Linux-only
+ *
+ * Copyright (c) 2015 - 2017, Přemysl Janouch <p.janouch@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+// Sources: ddcciv1r1.pdf, i2c-dev.c in Linux, ddccontrol source code,
+//   http://www.boichat.ch/nicolas/ddcci/specs.html was also helpful
+
+#include <sys/ioctl.h>
+
+#include <linux/i2c-dev.h>
+#ifndef I2C_FUNC_I2C
+// Fuck you, openSUSE, for fucking up the previous file, see e.g.
+// https://github.com/solettaproject/soletta/commit/427f47f
+#include <linux/i2c.h>
+#endif
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static void
+log_message_custom (void *user_data, const char *quote, const char *fmt,
+	va_list ap)
+{
+	(void) user_data;
+	FILE *stream = stdout;
+
+	fprintf (stream, PROGRAM_NAME ": ");
+	fputs (quote, stream);
+	vfprintf (stream, fmt, ap);
+	fputs ("\n", stream);
+}
+
+static void
+wait_ms (long ms)
+{
+	struct timespec ts = { 0, ms * 1000 * 1000 };
+	nanosleep (&ts, NULL);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+#define DDC_LENGTH_XOR 0x80
+
+enum
+{
+	DDC_ADDRESS_HOST          = 0x50,   ///< Bus master's base address
+	DDC_ADDRESS_DISPLAY       = 0x6E    ///< The display's base address
+};
+
+enum { I2C_WRITE, I2C_READ };
+
+enum
+{
+	DDC_GET_VCP_FEATURE       = 0x01,   ///< Request info about a feature
+	DDC_GET_VCP_FEATURE_REPLY = 0x02,   ///< Feature info response
+	DDC_SET_VCP_FEATURE       = 0x03    ///< Set or activate a feature
+};
+
+enum
+{
+	VCP_BRIGHTNESS            = 0x10,   ///< Standard VCP opcode for brightness
+	VCP_CONTRAST              = 0x12,   ///< Standard VCP opcode for contrast
+	VCP_INPUT_SOURCE          = 0x60    ///< Standard VCP opcode for input
+};
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static bool
+check_edid (int fd, struct error **e)
+{
+	uint8_t edid_req[] = { 0x00 };
+	uint8_t buf[8] = "";
+	struct i2c_msg bufs[] =
+	{
+		{ .addr = 0x50, .flags = 0,
+		  .len = 1, .buf = edid_req },
+		{ .addr = 0x50, .flags = I2C_M_RD,
+		  .len = sizeof buf, .buf = buf },
+	};
+
+	struct i2c_rdwr_ioctl_data data;
+	data.msgs = bufs;
+	data.nmsgs = 2;
+
+	if (ioctl (fd, I2C_RDWR, &data) < 0)
+		return error_set (e, "%s: %s", "ioctl", strerror (errno));
+	if (memcmp ("\x00\xFF\xFF\xFF\xFF\xFF\xFF\x00", buf, sizeof buf))
+		return error_set (e, "invalid EDID");
+	return true;
+}
+
+static bool
+is_a_display (int fd, struct error **e)
+{
+	struct stat st;
+	if (fstat (fd, &st) < 0)
+		return error_set (e, "%s: %s", "fstat", strerror (errno));
+
+	unsigned long funcs;
+	if (!(st.st_mode & S_IFCHR)
+	 || ioctl (fd, I2C_FUNCS, &funcs) < 0
+	 || !(funcs & I2C_FUNC_I2C))
+		return error_set (e, "not an I2C device");
+
+	return check_edid (fd, e);
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static bool
+ddc_send (int fd, unsigned command, void *args, size_t args_len,
+	struct error **e)
+{
+	struct str buf;
+	str_init (&buf);
+	str_pack_u8 (&buf, DDC_ADDRESS_HOST | I2C_READ);
+	str_pack_u8 (&buf, DDC_LENGTH_XOR | (args_len + 1));
+	str_pack_u8 (&buf, command);
+	str_append_data (&buf, args, args_len);
+
+	unsigned xor = DDC_ADDRESS_DISPLAY;
+	for (size_t i = 0; i < buf.len; i++)
+		xor ^= buf.str[i];
+	str_pack_u8 (&buf, xor);
+
+	struct i2c_msg msg =
+	{
+		// The driver unshifts it back
+		.addr = DDC_ADDRESS_DISPLAY >> 1, .flags = 0,
+		.len = buf.len, .buf = (uint8_t *) buf.str,
+	};
+
+	struct i2c_rdwr_ioctl_data data;
+	data.msgs = &msg;
+	data.nmsgs = 1;
+
+	bool failed = ioctl (fd, I2C_RDWR, &data) < 0;
+	str_free (&buf);
+	if (failed)
+		return error_set (e, "%s: %s", "ioctl", strerror (errno));
+	return true;
+}
+
+static bool
+ddc_read (int fd, unsigned *command, void *out_buf, size_t *n_read,
+	struct error **e)
+{
+	uint8_t buf[128] = "";
+	struct i2c_msg msg =
+	{
+		// The driver unshifts it back
+		.addr = DDC_ADDRESS_DISPLAY >> 1, .flags = I2C_M_RD,
+		.len = sizeof buf, .buf = buf,
+	};
+
+	struct i2c_rdwr_ioctl_data data;
+	data.msgs = &msg;
+	data.nmsgs = 1;
+
+	if (ioctl (fd, I2C_RDWR, &data) < 0)
+		return error_set (e, "%s: %s", "ioctl", strerror (errno));
+
+	struct msg_unpacker unpacker;
+	msg_unpacker_init (&unpacker, buf, sizeof buf);
+
+	uint8_t sender, length, cmd;
+	(void) msg_unpacker_u8 (&unpacker, &sender);
+	(void) msg_unpacker_u8 (&unpacker, &length);
+	(void) msg_unpacker_u8 (&unpacker, &cmd);
+
+	if (sender != (DDC_ADDRESS_DISPLAY | I2C_WRITE) || !(length & 0x80))
+		return error_set (e, "invalid response");
+	if (!(length ^= 0x80))
+		return error_set (e, "NULL response");
+
+	// TODO: also check the checksum
+
+	*command = cmd;
+	memcpy (out_buf, unpacker.data + unpacker.offset, (*n_read = length - 1));
+	return true;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+struct vcp_feature_readout
+{
+	uint8_t type;                       ///< Type of the value
+	int16_t max;                        ///< Maximum value
+	int16_t cur;                        ///< Current value
+};
+
+static bool
+vcp_get_feature (int fd, uint8_t feature, struct vcp_feature_readout *out,
+	struct error **e)
+{
+	uint8_t get_req[] = { feature };
+	if (!ddc_send (fd, DDC_GET_VCP_FEATURE, get_req, sizeof get_req, e))
+		return false;
+
+	wait_ms (40);
+
+	unsigned command = 0;
+	uint8_t buf[128] = "";
+	size_t len = 0;
+	if (!ddc_read (fd, &command, buf, &len, e))
+		return false;
+
+	if (command != DDC_GET_VCP_FEATURE_REPLY || len != 7)
+		return error_set (e, "invalid response");
+
+	struct msg_unpacker unpacker;
+	msg_unpacker_init (&unpacker, buf, len);
+
+	uint8_t result;     msg_unpacker_u8  (&unpacker, &result);
+	uint8_t vcp_opcode; msg_unpacker_u8  (&unpacker, &vcp_opcode);
+	msg_unpacker_u8  (&unpacker, &out->type);
+	msg_unpacker_i16 (&unpacker, &out->max);
+	msg_unpacker_i16 (&unpacker, &out->cur);
+
+	if (result == 0x01)
+		return error_set (e, "error reported by monitor");
+
+	if (result != 0x00
+	 || vcp_opcode != feature)
+		return error_set (e, "invalid response");
+
+	// These are unsigned but usually just one byte long
+	if (out->max < 0 || out->cur < 0)
+		return error_set (e, "capability range overflow");
+	return true;
+}
+